#!/usr/bin/env python3
"""
Rename files like `foo/bar.html` to `foo/bar/index.html` for prettier URLs.
"""
import re
import sys
from pathlib import Path
from typing import Dict


def replace_links(path: Path, replacements: Dict[str, str]):
    for filename in path.glob("**/*.html"):
        with filename.open("r+") as f:
            contents = f.read()
            f.truncate(0)
            f.seek(0)
            for source, target in replacements.items():
                contents = contents.replace(source, target)

            # Convert absolute links to relative.
            contents = re.sub(
                r'((?:href|src|root)\s*=\s*")((?:\.\./)+)([^\.])', r"\1/\3", contents
            )

            f.write(contents)


def main(path: Path):
    replacements: Dict[str, str] = {}
    for p in path.glob("**/*.html"):
        if str(p.parent) == ".":
            # Don't convert top-level files.
            continue

        if p.name == "index.html":
            # Don't convert top-level files.
            continue

        print(f"Converting {p}...")

        dir_path = p.parent / p.stem
        dir_path.mkdir(parents=True, exist_ok=True)

        new_path = dir_path / "index.html"
        p.rename(new_path)
        replacements[str(p.relative_to(path))] = f"{new_path.parent.relative_to(path)}/"

    replace_links(path, replacements)


if __name__ == "__main__":
    main(Path(sys.argv[1]))